Expression of Superoxide Dismutase Isoforms in Desmodesmus subspicatus Cells Exposed to Anthropogenic Contaminants
Wojciech Pokora1, Agnieszka Dettlaff-Pokora2, Zbigniew Tukaj1
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1Department of Plant Physiology, Faculty of Biology, University of Gdańsk,
Piłsudskiego 46, 81-378 Gdynia, Poland
2Department of Biochemistry, Medical University of Gdańsk,
Dębinki 1, 80-211 Gdańsk, Poland
Pol. J. Environ. Stud. 2011;20(3):605–610
Expression of superoxide dismutase (SOD) isoforms was assessed as a biochemical marker, allowing to estimate the toxicity of chemicals toward a population of microalga Desmodesmus subspicatus (Chlorophyta). The effect of low (EC10) and elevated (EC50) doses of cadmium chloride (Cd), anthracene (ANT), and chloridazon (CHd) on SOD activity and isoform profile, as well as the amount of biosynthesized protein of ascribed to chloroplast (Fe-SOD) and cytosol (Cu/Zn-SOD) superoxide dismutase, were analyzed. Activities of Mn- SOD, Cu/Zn-SOD, and two Fe-SOD isoforms were determined densitometrically by native polyacrylamide gel electrophoresis and specific staining for SOD activity. Fe-SOD and Cu/Zn-SOD protein amount was analyzed by the semi-quantitative blot technique. The toxicants tested had no effect on the activity of Fe-SOD 1 isoform, whereas Fe-SOD 2 activity increased significantly. Simultaneously, the amount of Fe-SOD 1 protein increased after low contaminant doses treatment, whereas the amount of Fe-SOD 2 increased in cells exposed to elevated Cd, ANT, and CHd concentrations. A significant increase in Cu/Zn-SOD protein amount was observed in cells treated with EC50 doses of ANT and Cd, as well as CHd in concentrations corresponding to the EC10 value. At the same time, the activity of Cu/Zn-SOD increased in D. subspicatus cells exposed to an elevated dose of CHd. We have found that in the cells of D. subspicatus, the induction of Fe-SOD 1 and Cu/Zn-SOD Csd2 biosynthesis responds to xenobiotic-mediated stress level. The increase in the amount of chloroplastic Fe-SOD 1 and Cu/Zn-SOD Csd2 isoforms may be a sensitive biochemical marker of stress conditions, revealing the effects of low doses of aquatic contaminants on green algae.